1. Field of the Invention
This invention relates generally to the field of packaging, and more specifically to the field of hot fill type containers.
2. Description of the Related Technology
Hot fill containers are designed to be used with the conventional hot fill process, in which a liquid product such as fruit juice is introduced into the container while warm or hot, as appropriate, for sanitary packaging of the product.
After filling, such containers undergo significant volumetric shrinkage as a result of the cooling of the product within the sealed container. Hot fill type containers accordingly must be designed to have the capability of accommodating such shrinkage. Typically this has been done by incorporating one or more concave vacuum panels into the side wall of the container that are designed to flex inwardly as the volume of the product within the container decreases as a result of cooling.
Conventional vacuum panels are ordinarily framed or caged within the sidewall of the container by the presence of inwardly extending panel portions that are located near the periphery of the vacuum panel. Most of the volumetric contraction capability of the vacuum panel is accomplished by flexure of an interior portion of the vacuum panel that is framed or caged by the inwardly extending panel portions. Unfortunately, the contraction capability of vacuum panels in smaller containers has been limited to less than what is desired in many cases because the maximum surface area of the interior portions of the vacuum panels is limited by framing of the vacuum panel.
Hot fill containers must be designed to be strong enough in the areas outside of the vacuum panel regions so that the deformation that occurs as a result of the volumetric shrinkage of a product within the container is substantially limited to the portions of the container that are designed specifically to accommodate such shrinkage. In addition, since filled containers are often stacked on top of one another for transportation and distribution, the sidewall of such containers must be designed to have sufficient column strength in order to endure a predetermined minimum vertical load. It is important that such column strength not be degraded as the shape of the container changes as result of volumetric shrinkage within the container. To that end, conventional designs for hot fill containers typically included a plurality of vertically extending non-recessed sidewall portions serving as posts between the vacuum panel areas in order to impart additional column strength.
Most hot fill type containers are fabricated from polyethylene terephthalate, which is otherwise known as PET. PET possesses excellent characteristics for such containers, but PET resin is relatively expensive. Accordingly, a PET container design that reduces the amount of material that is used without sacrificing performance will provide a significant competitive advantage within the packaging industry. The presence of numerous surface features such as deeply recessed vacuum panels requiring extensive framing on conventional container designs has inhibited lightweighting of the container to some extent.
A need has existed for an improved hot fill container design provides optimal volumetric efficiency, material usage and container strength and that is particularly suited for use with smaller containers.